1. Field of the Invention
The present invention is related to a connector assembly with multiple rows and columns of conductive elements, especially to a connector assembly having a plurality of inner circuit boards mounted therein to form needed conductive paths to connect with a daughtercard and a backplane assembly.
2. Description of the Related Art
Most of backplane assemblies used in a computation or communication device have at least one primary circuit board with the basic specialized function which need to combine with other functional electronic extension cards/circuit boards so that the whole assembly they belong to can achieve diverse, improvable and massively repeated performance. Therefore, a plurality of interconnection devices like board-to-board electrical connectors used to connect the primary circuit board and other extension circuit boards/cards then are broadly adopted in the backplane assembly. Due to multiple rows and columns of conductive elements or contacts such an interconnection device may have, the perfect and cheap way for manufacturing, assembling and mounting the interconnection device is difficult to find out or achieve at present. Originally, the conventional backplane connector design uses a large insulative housing with a plurality of holes for the inserted installation of contacts. However, this kind of designs is not good and convenient enough for the high density and small-pitched requirement of an interconnection device recently. Specially, the complicated and necessary assembling process causes the high cost of the final product and time consuming. Therefore, it is known to provide each column of contacts as a separate module that includes one vertical array of contacts having an overmolded carrier. Multiple modules then are integrally installed in a connector housing to form a complete connector. U.S. Pat. Nos. 5,066,236 and 5,664,968 both show such a connector structure. Generally, all of the modules in such a connector are substantially identical. But different types of modules sometimes are needed in a connector in order to accommodate different electrical characteristics of signals through the connector. Besides, due to continuing trends toward miniaturization and improved electrical performance by the electronics industry, requirements for greater conductive element/contact density and higher electrical speeds are constantly being promulgated. These requirements lead to design conflicts, especially when electrical speeds are in the range of approximately 500 megahertz and above, due to the fact that increasing the contact density places the conductive elements/contacts in closer proximity to each other, thereby leading to crosstalk between neighboring conductive elements/contacts in different signal pairs. Thus, as introduced in U.S. Pat. No. 5,104,341 and 6,299,484, some ground reference means are disposed between every two signal modules to reduce crosstalk induced therebetween.
However, new overmolded technology developing recently shows possibly high production cost may be caused because more and more minimized conductive elements should be assembled together in a small-sized plastic block. It is much difficult to position these high density arranged conductive elements in a overmolding mold due to the high plastic injection pressure and scarce space between these elements. A precise and complicate mold that usually costs high is needed to achieve the production. Therefore, some other substitutes like a small circuit board are considered. Robin et al. U.S. Pat. No. 4,571,014 and Paagman U.S. Pat. No. 5,924,899 both show a plurality of inner circuit boards installed inside a backplane connector. Each conductive path on these circuit boards can be thinner and closer to each other than a separate stamping contact of the overmolded module though a perfect small circuit board costs high too. An extra solder tail or a mating contact for every conductive path on the circuit board is needed and most of them should be soldered onto one of the circuit boards first before the circuit board is installed into the backplane connector. And the solder joints of every circuit board may be hurt or broken when the backplane connector is mated because the mating force applied on every circuit board may be transferred to its solder joints right away. More fixing or positioning features have to be considered and adopted to overcome this situation and result in a higher product cost.
Therefore, an object of the present invention is to provide an electrical connector used in a backplane application with inner circuit boards installed therein to achieve a better electrical performance by using a method of assembling and fastening the inner circuit boards and other parts of the connector along a direction vertical to its mating direction so that they can avoid any unnecessary displacement during the processes of mating or board-mounting.
Another object of the present invention is to provide an electrical connector having effective and useful fixing mechanism to fasten parts, like inner circuit boards, inside the connector, which still contributes easily assembling of parts and functions without any complicated structure.
Another object of the present invention is to provide an electrical connector having larger tolerance to undesired mating displacement of inner circuit boards installed therein and maintaining better electrical performance in a vibration circumstance.
To obtain the above objects, an electrical connector in accordance with the present invention includes a top housing and a bottom housing to form a receiving space therebetween. A plurality of parallel partitions extends respectively from the inner face of the top and bottom housing and protruding into the receiving space. Inner circuit boards with traces thereon are respectively inserted and stay in the space between every two partitions of either the top housing or the bottom housing. Besides, pairs of signal contacts and grounding plates are installed in the bottom housing. The signal contact pairs are respectively received inside every partition in one row and exposed their engaging arms out of one surface of the partition while each grounding plate is seated and abutting against the other surface of every partition respectively. Each of the inner circuit boards has pairs of signal traces on one surface and a grounding layer formed on the other so that they can be engaged with the signal contact pairs and grounding plates installed in the bottom housing when the connector is assembled.
Specially, compressible ridges are disposed on the inner top face of the top housing between every two partitions in spaced-apart relationship. And holes are formed on the top housing and the bottom housing respectively and can be treated as a pair because each hole on the top housing and its related one on the bottom housing are located in the same plane right between two spaced-apart partitions. Two projections corresponding to the holes extend out of edges of every inner circuit board and are inserted into the holes when the connector is assembled. Meanwhile, a plurality of stops abutting against the inner bottom face of the bottom housing is stamped out of the surface of each grounding plate. Every one of the inner circuit board is rested on the top of the stops of a corresponding grounding plate and is pressed by the compressible ridges of the top housing in order to be positioned when the top and bottom housings are assembled as a whole connector along the direction parallel to the mating face of the connector. Therefore, the inner circuit boards can be held in position inside the connector though they are not actually fixed therein. The effective engagement between the boards and conductors in the bottom housing will be continuously maintained by projections of inner circuit boards and holes of the housings, and a flexible mechanism including ridges cooperating with stops of grounding plates when the connector is mated with its complementary connector. And due to the separable engagement between the inner circuit boards mostly received in the top housing and the conductors, pairs of signal contacts and grounding plates, received in the bottom housing and the fact of the top housing being removably latched above the bottom housing, the inner circuit boards can be dismantled and replaced anytime even though the connector is mounted on a printed circuit board and no special treatment or process like reflow is needed.
Furthermore, the projections of every inner circuit board are inserted into the holes of the top and bottom housings respectively along a direction parallel to the mating face of the connector, which is the same direction as the assembling direction of the top and bottom housings, so that the top housing is latched on the bottom housing as well as all of the inner circuit boards are installed and fixed inside the connector at the same time. And projections of the inner circuit boards will stop any unnecessary movement of the inner boards along the mating direction when the connector is mated with its complementary connector.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description of the present embodiment when taken in conjunction with the accompanying drawings.